[for-next,v7,3/5] nvme: refactor nvme_alloc_user_request

Commit Message

Kanchan Joshi Sept. 9, 2022, 10:21 a.m. UTC

Separate this out to two functions with reduced number of arguments.

Comments

Christoph Hellwig Sept. 20, 2022, 12:02 p.m. UTC | #1

On Fri, Sep 09, 2022 at 03:51:34PM +0530, Kanchan Joshi wrote:
> Separate this out to two functions with reduced number of arguments.
> _
> Signed-off-by: Kanchan Joshi <[e-mail]>
> ---
>  drivers/nvme/host/ioctl.c | 116 ++++++++++++++++++++++----------------
>  1 file changed, 66 insertions(+), 50 deletions(-)
> 
> diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
> index 548aca8b5b9f..cb2fa4db50dd 100644
> --- a/drivers/nvme/host/ioctl.c
> +++ b/drivers/nvme/host/ioctl.c
> @@ -65,18 +65,10 @@ static int nvme_finish_user_metadata(struct request *req, void __user *ubuf,
>  }
>  
>  static struct request *nvme_alloc_user_request(struct request_queue *q,
> +		struct nvme_command *cmd, unsigned timeout,
>  		blk_opf_t rq_flags, blk_mq_req_flags_t blk_flags)

I think we can also drop the timeout flag here, which seems like it
can be handled cleaner in the callers.
to set it can just do that.

> +static int nvme_map_user_request(struct request *req, void __user *ubuffer,
> +		unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
> +		u32 meta_seed, void **metap, bool vec)
> +{
> +	struct request_queue *q = req->q;
> +	struct nvme_ns *ns = q->queuedata;
> +	struct block_device *bdev = ns ? ns->disk->part0 : NULL;
> +	struct bio *bio = NULL;
> +	void *meta = NULL;
> +	int ret;
> +
> +	if (!ubuffer || !bufflen)
> +		return 0;

I'd leave these in the callers and not call the helper if there is
no data to transfer.

> +
> +	if (!vec)
> +		ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
> +			GFP_KERNEL);
> +	else {
> +		struct iovec fast_iov[UIO_FASTIOV];
> +		struct iovec *iov = fast_iov;
> +		struct iov_iter iter;
> +
> +		ret = import_iovec(rq_data_dir(req), ubuffer, bufflen,
> +				UIO_FASTIOV, &iov, &iter);
> +		if (ret < 0)
>  			goto out;
> +		ret = blk_rq_map_user_iov(q, req, NULL, &iter, GFP_KERNEL);
> +		kfree(iov);

To me some of this almost screams like lifting the vectored vs
not to the block layer into a separate helper.

> +	}
> +	bio = req->bio;
> +	if (ret)
> +		goto out_unmap;

This seems incorrect, we don't need to unmap if blk_rq_map_user*
failed.

> +	if (bdev)
> +		bio_set_dev(bio, bdev);

I think we can actually drop this now - bi_bdev should only be used
by the non-passthrough path these days.

> +	if (bdev && meta_buffer && meta_len) {
> +		meta = nvme_add_user_metadata(bio, meta_buffer, meta_len,
> +				meta_seed, req_op(req) == REQ_OP_DRV_OUT);
> +		if (IS_ERR(meta)) {
> +			ret = PTR_ERR(meta);
> +			goto out_unmap;
>  		}
> +		req->cmd_flags |= REQ_INTEGRITY;
> +		*metap = meta;

And if we pass the request to nvme_add_user_metadata, that can set
REQ_INTEGRITY.  And we don't need this second helper at all.

Kanchan Joshi Sept. 22, 2022, 3:46 p.m. UTC | #2

On Tue, Sep 20, 2022 at 02:02:26PM +0200, Christoph Hellwig wrote:

I should be able to fold all the changes you mentioned.

Kanchan Joshi Sept. 23, 2022, 9:25 a.m. UTC | #3

>> +
>> +	if (!vec)
>> +		ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
>> +			GFP_KERNEL);
>> +	else {
>> +		struct iovec fast_iov[UIO_FASTIOV];
>> +		struct iovec *iov = fast_iov;
>> +		struct iov_iter iter;
>> +
>> +		ret = import_iovec(rq_data_dir(req), ubuffer, bufflen,
>> +				UIO_FASTIOV, &iov, &iter);
>> +		if (ret < 0)
>>  			goto out;
>> +		ret = blk_rq_map_user_iov(q, req, NULL, &iter, GFP_KERNEL);
>> +		kfree(iov);
>
>To me some of this almost screams like lifting the vectored vs
>not to the block layer into a separate helper.
>
So I skipped doing this, as cleanup is effective when we have the
elephant; only a part is visible here. The last patch (nvme fixedbufs
support) also changes this region. 
I can post a cleanup when all these moving pieces get settled.

>> +	}
>> +	bio = req->bio;
>> +	if (ret)
>> +		goto out_unmap;
>
>This seems incorrect, we don't need to unmap if blk_rq_map_user*
>failed.
>
>> +	if (bdev)
>> +		bio_set_dev(bio, bdev);
>
>I think we can actually drop this now - bi_bdev should only be used
>by the non-passthrough path these days.
Not sure if I am missing something, but this seemed necessary. bi_bdev was
null otherwise.

Did all other changes.

Patch

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 548aca8b5b9f..cb2fa4db50dd 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -65,18 +65,10 @@  static int nvme_finish_user_metadata(struct request *req, void __user *ubuf,
 }
 
 static struct request *nvme_alloc_user_request(struct request_queue *q,
-		struct nvme_command *cmd, void __user *ubuffer,
-		unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
-		u32 meta_seed, void **metap, unsigned timeout, bool vec,
+		struct nvme_command *cmd, unsigned timeout,
 		blk_opf_t rq_flags, blk_mq_req_flags_t blk_flags)
 {
-	bool write = nvme_is_write(cmd);
-	struct nvme_ns *ns = q->queuedata;
-	struct block_device *bdev = ns ? ns->disk->part0 : NULL;
 	struct request *req;
-	struct bio *bio = NULL;
-	void *meta = NULL;
-	int ret;
 
 	req = blk_mq_alloc_request(q, nvme_req_op(cmd) | rq_flags, blk_flags);
 	if (IS_ERR(req))
@@ -86,49 +78,61 @@  static struct request *nvme_alloc_user_request(struct request_queue *q,
 	if (timeout)
 		req->timeout = timeout;
 	nvme_req(req)->flags |= NVME_REQ_USERCMD;
+	return req;
+}
 
-	if (ubuffer && bufflen) {
-		if (!vec)
-			ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
-				GFP_KERNEL);
-		else {
-			struct iovec fast_iov[UIO_FASTIOV];
-			struct iovec *iov = fast_iov;
-			struct iov_iter iter;
-
-			ret = import_iovec(rq_data_dir(req), ubuffer, bufflen,
-					UIO_FASTIOV, &iov, &iter);
-			if (ret < 0)
-				goto out;
-			ret = blk_rq_map_user_iov(q, req, NULL, &iter,
-					GFP_KERNEL);
-			kfree(iov);
-		}
-		if (ret)
+static int nvme_map_user_request(struct request *req, void __user *ubuffer,
+		unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
+		u32 meta_seed, void **metap, bool vec)
+{
+	struct request_queue *q = req->q;
+	struct nvme_ns *ns = q->queuedata;
+	struct block_device *bdev = ns ? ns->disk->part0 : NULL;
+	struct bio *bio = NULL;
+	void *meta = NULL;
+	int ret;
+
+	if (!ubuffer || !bufflen)
+		return 0;
+
+	if (!vec)
+		ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
+			GFP_KERNEL);
+	else {
+		struct iovec fast_iov[UIO_FASTIOV];
+		struct iovec *iov = fast_iov;
+		struct iov_iter iter;
+
+		ret = import_iovec(rq_data_dir(req), ubuffer, bufflen,
+				UIO_FASTIOV, &iov, &iter);
+		if (ret < 0)
 			goto out;
-		bio = req->bio;
-		if (bdev)
-			bio_set_dev(bio, bdev);
-		if (bdev && meta_buffer && meta_len) {
-			meta = nvme_add_user_metadata(bio, meta_buffer, meta_len,
-					meta_seed, write);
-			if (IS_ERR(meta)) {
-				ret = PTR_ERR(meta);
-				goto out_unmap;
-			}
-			req->cmd_flags |= REQ_INTEGRITY;
-			*metap = meta;
+		ret = blk_rq_map_user_iov(q, req, NULL, &iter, GFP_KERNEL);
+		kfree(iov);
+	}
+	bio = req->bio;
+	if (ret)
+		goto out_unmap;
+	if (bdev)
+		bio_set_dev(bio, bdev);
+	if (bdev && meta_buffer && meta_len) {
+		meta = nvme_add_user_metadata(bio, meta_buffer, meta_len,
+				meta_seed, req_op(req) == REQ_OP_DRV_OUT);
+		if (IS_ERR(meta)) {
+			ret = PTR_ERR(meta);
+			goto out_unmap;
 		}
+		req->cmd_flags |= REQ_INTEGRITY;
+		*metap = meta;
 	}
 
-	return req;
+	return ret;
 
 out_unmap:
 	if (bio)
 		blk_rq_unmap_user(bio);
 out:
-	blk_mq_free_request(req);
-	return ERR_PTR(ret);
+	return ret;
 }
 
 static int nvme_submit_user_cmd(struct request_queue *q,
@@ -141,13 +145,16 @@  static int nvme_submit_user_cmd(struct request_queue *q,
 	struct bio *bio;
 	int ret;
 
-	req = nvme_alloc_user_request(q, cmd, ubuffer, bufflen, meta_buffer,
-			meta_len, meta_seed, &meta, timeout, vec, 0, 0);
+	req = nvme_alloc_user_request(q, cmd, timeout, 0, 0);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	bio = req->bio;
+	ret = nvme_map_user_request(req, ubuffer, bufflen, meta_buffer,
+			meta_len, meta_seed, &meta, vec);
+	if (ret)
+		goto out;
 
+	bio = req->bio;
 	ret = nvme_execute_passthru_rq(req);
 
 	if (result)
@@ -157,6 +164,7 @@  static int nvme_submit_user_cmd(struct request_queue *q,
 						meta_len, ret);
 	if (bio)
 		blk_rq_unmap_user(bio);
+out:
 	blk_mq_free_request(req);
 	return ret;
 }
@@ -418,6 +426,7 @@  static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 	blk_opf_t rq_flags = 0;
 	blk_mq_req_flags_t blk_flags = 0;
 	void *meta = NULL;
+	int ret;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
@@ -457,13 +466,17 @@  static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 		rq_flags |= REQ_POLLED;
 
 retry:
-	req = nvme_alloc_user_request(q, &c, nvme_to_user_ptr(d.addr),
-			d.data_len, nvme_to_user_ptr(d.metadata),
-			d.metadata_len, 0, &meta, d.timeout_ms ?
-			msecs_to_jiffies(d.timeout_ms) : 0, vec, rq_flags,
-			blk_flags);
+	req = nvme_alloc_user_request(q, &c,
+			d.timeout_ms ? msecs_to_jiffies(d.timeout_ms) : 0,
+			rq_flags, blk_flags);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
+
+	ret = nvme_map_user_request(req, nvme_to_user_ptr(d.addr),
+			d.data_len, nvme_to_user_ptr(d.metadata),
+			d.metadata_len, 0, &meta, vec);
+	if (ret)
+		goto out_err;
 	req->end_io = nvme_uring_cmd_end_io;
 	req->end_io_data = ioucmd;
 
@@ -486,6 +499,9 @@  static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 
 	blk_execute_rq_nowait(req, false);
 	return -EIOCBQUEUED;
+out_err:
+	blk_mq_free_request(req);
+	return ret;
 }
 
 static bool is_ctrl_ioctl(unsigned int cmd)